An unexpected rock collapse happened in Rongxian County, Zigong. One person has been confirmed dead. Why did the stone suddenly fall?

An unexpected rock collapse happened in Rongxian County, Zigong. One person has been confirmed dead. Why did the stone suddenly fall?

1. Due to the weather and terrain. Landslide is the collapse of rocks under the action of gravity, which mostly occurs in steep places in mountainous areas. Rockfall falls naturally, and wet weather should be one of the main reasons. Rock collapse refers to the geological phenomenon that the rock mass on the steep slope breaks away from the parent rock under the action of gravity, suddenly collapses violently from the height and accumulates at the foot of the slope. Rockfall disasters widely exist in all kinds of hard rocks. Carbonate rocks, clastic rocks and metamorphic rocks with broken structure or weak interlayer are particularly prone to rock collapse. Large-scale falling rocks will destroy mines and houses, block traffic and cause serious casualties and property losses.

2. It is the most widely developed fault structure in the upper crust. Primary joints, formed during diagenesis, such as mud cracks formed by shrinkage of sedimentary rocks or columnar joints formed by cooling shrinkage of igneous rocks; Structural joints, formed by structural deformation; Unstructured joints, that is, joints formed by external dynamic action (such as weathering, landslide or ground sliding), are usually confined to shallow surfaces. At the edge of the cliff, rain erosion and weathering are the main factors to increase rock texture (cracks), so the rocks on the cliff will always collapse.

3. This research "is a very important research, which makes people have a new understanding of rock topography." Geoffrey Moore, a geologist in Salt Lake City, said: "The distortion of 1 cm every day is no small matter." He said that daily temperature fluctuations will also exert such pressure on layered sandstone, causing them to crack, which may cause these types of rocks to fall off the cliff. Stephen martel, a geologist at the University of Hawaii, said that before this study, researchers largely ignored the thermal stress in rocks. But this study "includes measurement and theoretical work in two fields." Thermal stress is very important. When combined with other stresses in the rock, the stress caused by temperature change is "the last straw to crush the camel", which causes the rock to fall off the cliff, martel said.